Some turbine monitoring instruments used for measuring vibration, eccentricity, elongation, or elongation difference of a rotor, casing, or the like of turbine generators or electric pumps for nuclear or thermal power generation or private power generation employ a cybersecurity function. Generally, a turbine monitoring instrument measures vibration of a revolving shaft or a casing in a turbine generator or electric pump or elongation or elongation difference of the revolving shaft in the turbine generator or electric pump, or the like. Moreover, the turbine monitoring instrument transfers, to a host control device such as a distributed control system (DCS) or electric hydraulic control (EHC) disposed in a remote place, information related to a measurement result (e.g. measurement value or alarm) of vibration of the revolving shaft or casing in the turbine generator or electric pump or elongation or elongation difference of the revolving shaft in the turbine generator or electric pump, or the like.
Some of cybersecurity functions employed to the turbine monitoring instruments ensure security by permitting change of setting values only when a password is input to a personal computer (PC) that can change the setting values having been set to the turbine monitoring instrument (monitor) and the input password is correct.
Alternatively, some of cybersecurity functions employed to turbine monitoring instruments ensure security by providing a hardware key for setting setting values or the like to the turbine monitoring instrument and thereby changing setting values only when an operator operates the hardware key for settings to cause the turbine monitoring instrument to be switched over to a RUN state, where the setting value or the like can be changed.
Furthermore, in recent years, a host control device, storing data digitalized from the measurement result or the like by the turbine monitoring instrument, monitors at all times the turbine monitoring instrument connected thereto via a network. In such circumstances, especially in a nuclear power plant or the like, important devices (such as turbine monitoring instruments) are targeted in cyber-attacks more frequently.
With a cybersecurity function using a password, however, once the password is solved, setting values having been set to a turbine monitoring instrument may be easily changed and thus a monitoring target of the turbine monitoring instrument may fall into chaos. Alternatively, a cybersecurity function using a hardware key for settings requires key operation to cause the RUN state with the hardware key for settings every time the setting values or the like having been set to the turbine monitoring instrument are changed and management or the like is required for the hardware key for settings to prevent losing or the like of the hardware key for settings. Moreover, when a spare key is produced, it becomes difficult that the hardware key for settings plays a role as the cybersecurity function.
In general, an according to an embodiment, a communication control device is provided with a converter and a controller. The converter is input with a second digital data signal prior to input of a first digital data signal and outputs an analog data signal which is an analog signal converted into from the second digital data signal. The first digital data signal is output to a destination device. The controller invalidates the first digital data signal when a voltage corresponding to the analog data signal does not coincide with a predetermined output permission voltage and validates the first digital data signal when the voltage corresponding to the analog data signal coincides with the output permission voltage.